I feel like three-to-four weeks may be a better minimum, but also clearly a luxury that most can't afford.
Not only are we accustomed to the two-day weekend, but there's also the rest of life to squeeze into a couple hours a day and then two days every week.
Due to strange sleeping habits, I have an extremely flexible schedule. I still put in an average of 40 hours a week, but sometimes it's nights, sometimes days, sometimes all within a couple days.
Even if I have four days left for a "weekend", I still have to account for all the things living in a modern society entail: paying bills, buying groceries, doing laundry, washing dishes, managing accounts, maintaining my house and car, mowing the lawn, shoveling snow, buying toilet paper and paper towels, etc. Sure, I can automate some of these things by way of a dishwasher, laundry services, and grocery delivery, but there's still attention required†.
Of course, and more importantly, there are the things I _want_ to do, like spend time with my wife, see friends and family, make fancy bread, tweak my home automation, sleep, and so on.
Even without a commute, all of these things fill my entire week. I think this is the source of time going by so quickly with age. The responsibility of maintaining a happy and stable life takes a good deal of maintenance. Add to that, the fact that I now require 6-8 hours of sleep when 4-5 used to be plenty for me, and the fact that we want to start a family, and I don't think 2 days a week will _ever_ cut it.
> I often likewise waste time on nights and weekends
Although it wasn't clear in my wording, I don't actually feel this time is truly wasted. The brain and body require time off and I'm more than happy to oblige.
† I have a note on my Instacart account that says "please use your best judgement - never call me unless you can't get to my front door"